The plastics industry has long used particulate fillers and selected reinforcing fibers within thermosetting resins, and more recently within thermoplastic resins. Also, the automotive industry has long used resin impregnated fiber mats to form trunk liners, door panels, etc. This technology has also led to the development of certain thermoformable compositions containing natural fibers, and thermosetting or thermoplastic polymeric materials.
In U.S. Pat. No. 3,325,345 to Hider is disclosed the formation of a water-laid product comprising relatively fine fibrillated cellulosic fibers, and a particulate thermoplastic polymer. The relatively fine nature of the cellulosic fibers has tended to complicate water removal during the formation of the product.
In U.S. Pat. No. 4,451,539 to Vallee is disclosed a thermoformable material comprising reinforcing fibers, a fibrous polyolefin dough, particulate thermoplastic polymer, and a binder. The presence of the fibrous polyolefin dough in a substantial concentration has added significantly to the cost of the product. Also, the binder has added a significant production cost.
In British Patent No. 1,453,503 to Solvey & Cie is disclosed a thermoformable sheet comprising vegetable fibers and synthetic polymer fibers. Inorganic fillers may be included in such compositions. The presence of the synthetic polymer fibers in a substantial concentration has added a significant production cost.
The use of low density particulate fillers in certain polymers and fiber-containing sheet products has been disclosed in the past.
It is an object of the present invention to provide a novel thermoformable mat of reduced density having acceptable mechanical properties which can be produced on a relatively economical basis.
It is an object of the present invention to provide a novel soft and flexible thermoformable mat of reduced density which can be readily handled and transported without damage prior to utilization.
It is an object of the present invention to provide a novel thermoformable mat of reduced density having satisfactory mechanical properties which can be formed and molded on a relatively expeditious basis.
It is an object of the present invention to provide a novel thermoformable mat of reduced density which incorporates thermoplastic polymeric components and overcomes the lengthy molding times associated with compositions of the prior art which incorporate thermosetting polymeric materials.
It is an object of the present invention to provide a novel thermoformed laminate comprising cellulosic fibers and consolidated thermoplastic resin which exhibits superior impact resistance when compared to products which employ a thermoset resin or unfilled injection molded plastics.
It is an object of the present invention to provide a novel thermoformable mat of reduced density which is substantially free of a costly binder.
It is an object of the present invention to provide a novel thermoformable mat of reduced density having satisfactory mechanical properties which contains a relatively low concentration of relatively expensive thermoplastic polymer fibrils together with less expensive non-fibrous thermoplastic synthetic polymer particles.
It is another object of the present invention to provide a novel thermoformable mat of reduced density which while stacked together with similar mats of greater density on at least the upper and lower surface may be subjected to heat and pressure to accomplish densification and thermal bonding within and between adjoining sheets to form a laminate.
It is another object of the present invention to provide a novel thermoformed laminate of the skin-core type wherein density of the interior is less than the density of the surfaces.
It is a further object of the present invention to provide a novel thermoformed laminate of good uniformity and reduced density which can be used to advantage as a shaped rigid panel for use as an inner automobile door liner or in similar end uses which require a rigid sheet or panel having a predetermined configuration.
It is a further object of the present invention to provide a novel thermoformed laminate of the skin-core type which possesses superior physical properties such as bending modules, heat deflection, etc.
It is yet another object of the present invention to provide a novel thermoformed laminate of reduced density to which a decorative surface optionally may be readily applied.
These and other objects, as well as the scope, nature, and utilization of the claimed invention will be apparent from the following detailed description and appended claims.